Wireless devices may communicate with other devices using multiple technologies, including wireless local area network (WLAN) signals (e.g., 900 MHz, 2.4 GHz, 5 GHz, and 60 GHz signaling), BLUETOOTH® (BT or Bluetooth) signals, near field communication (NFC) signals, and cellular signals such as long term evolution (LTE) signals. For example, a wireless device may include a transmitter to transmit communication signals to other devices, and may include a receiver to receive communication signals from other devices.
Some transmitted communication signals may include one or more undesired signal components. These undesired signal components may include unwanted harmonics of clock signals. These unwanted harmonics, which are commonly referred to as frequency spurs, may degrade performance of the device.
Many wireless devices include crystal oscillators to generate clock signals. For example, a crystal oscillator may be used to generate a highly accurate reference clock signal that, in turn, may be used to generate radio-frequency (RF) signals such as carrier signals and local oscillator (LO) signals. Unwanted harmonics of the clock signal generated by the crystal oscillator may be coupled into other sensitive circuits and components of the wireless device, and may undesirably appear at outputs of the wireless device's transceiver.
Thus, it is desirable to reduce or eliminate these unwanted clock signal harmonics.